Keep rollouts and the merges they answer in the rollouts bucket (issue 1092)

Once chain_moved records the kind, a plan is a key of the rollouts bucket under its id and the open batch is the same key in state assembling. A save refuses a copy another save moved since (the plan's own Revision, kept in its value, counts saves) and keeps the merges the record holds, so a copy read before a merge moved cannot lay it back. The merges a batch or walk answers are the record's held field, with the columns the table had; a merge no plan answers stays, flagged, in the record that held it last, or in the record kept for those. A merge moved to a plan is written to the receiving record first and then taken from the giving one; one found in both is read from the one it entered last and repaired at the next cut. Plans and merges are read from a view kept by one watch of the bucket. A bus that does not answer, a lease lost and a key moved are now not-now like the store being away, so a merge whose plan could not be written is held and handed over again, never acknowledged. The start moves release_plan and batched_merge into the bucket, one kind, counted against both tables.

cmd/mesh-controller/batches.go

@@ -219,10 +219,10 @@ func (f following) hearMerge(ctx context.Context, m link.SourceMoved, now time.T
 		}
 		if p.Batch() {
 			if err := keepBatch(ctx, inv, &p, now, ""); err != nil {
-				return notNow(err)
+				return unsaved(err)
 			}
 		} else if err := nameMerges(ctx, inv, &p); err != nil {
-			return notNow(err)
+			return unsaved(err)
 		}
 		fmt.Printf("%s merged into %s (%.8s) after a later merge of its branch was put in %s (%s): that %s "+
 			"answers it\n", repository, m.Base, m.Commit, p.ID, p.State, walkOrBatch(p))
@@ -239,7 +239,7 @@ func (f following) hearMerge(ctx context.Context, m link.SourceMoved, now time.T
 	}
 	holdFor(&batch, m.Head, waits, holding, own, now)
 	if err := keepBatch(ctx, inv, &batch, now, ""); err != nil {
-		return notNow(err)
+		return unsaved(err)
 	}
 	fmt.Printf("%s merged into %s (%.8s); %s, it joins %s — %s\n", repository, m.Base, m.Commit, why, batch.ID,
 		batchWords(batch, now))
@@ -820,6 +820,12 @@ func nameMerges(ctx context.Context, inv *inventory.Inventory, p *inventory.Plan
 // walk open, behind which it is said queued (cutUnrelated). While the search runs everything waits.
 func cutBatchesHeld(ctx context.Context, open *stores, now time.Time) error {
 	inv := open.inventory
+	// A merge found in two records is the half-done move of a crash: put right before anything is decided from it.
+	if repaired, err := inv.RepairMerges(ctx); err != nil {
+		return err
+	} else if repaired > 0 {
+		fmt.Printf("%d merge(s) found in two plans, the half of a move a restart interrupted, are kept by the plan they were moved to\n", repaired)
+	}
 	if err := searchAfterFailures(ctx, inv); err != nil {
 		return err
 	}